150,920 research outputs found
Use of Aluminum-Foil and Oat-Straw Mulches for Controlling Aster Leafhopper, \u3ci\u3eMacrosteles Fascifrons\u3c/i\u3e (Homoptera: Cicadellidae), and Aster Yellows in Carrots.
Aluminum-foil and oat-straw mulches significantly (P \u3c 0.05) reduced aster leafhopper numbers on carrots compared to an untreated control and a malathion spray treatment during the first half of the growing season. The amount of reflected light was significantly higher in both aluminum-foil and oat-straw mulched plots compared to unmulched treatments. Mulch effectiveness decreased when the closing carrot canopy reduced surface area of reflective mulches and amount of reflected light The percentage of aster yellows-infected plants was significantly lower (P \u3c 0.05) in aluminum-foil and straw mulches and in the malathion spray plots compared to the untreated control. Results demonstrated that aluminum-foil and straw mulches gave control of aster leafhoppers and aster yellows in carrots equal to that of a conventional insecticide spray program
The Influence of Reflective Mulches and Lettuce Types on the Incidence of Aster Yellows and Abundance of its Vector, \u3ci\u3eMacrosteles Fascifrons\u3c/i\u3e (Homoptera: Cicadelidae), in Minnesota
Five commercial lettuce cultivars representing different genetic types were grown through aluminum-coated paper, through black polyethylene film, and on bare soil. For each variety, the aluminum mulch reduced the numbers of Macrosteles fascifrons (St~l), reduced the incidence of aster yellows, and increased yields when compared to uncovered controls. The head lettuce cultivar \u27Minetto\u27 was most susceptible on unmulched plots (74.3%) while the leaf cultivar \u27Grand Rapids\u27 was least susceptible (33.8%). The latter also had the greatest infestation of leafhoppers which may indicate either resistance to the aster yellows agent or shorter feeding times by the vector leafhopper. The abundance of aster leafhoppers on the romaine cultivar \u27Valmaine\u27, the butter head cultivar \u27Buttercrunch\u27, and the bibb cultivar \u27Summer Bibb\u27 was much lower than that of the other two and might explain the lower percentage of aster yellows on these types as compared with \u27Minetto\u27
Evaluation of TanDEM-X DEMs on selected Brazilian sites: comparison with SRTM, ASTER GDEM and ALOS AW3D30
A first assessment of the TanDEM-X DEMs over Brazilian territory is presented
through a comparison with SRTM, ASTER GDEM and ALOS AW3D30 DEMs in seven study
areas with distinct geomorphological contexts, vegetation coverage and land
use. Visual analysis and elevation histograms point to a finer effective
spatial resolution of TanDEM-X compared to SRTM and ASTER GDEM. In areas of
open vegetation, TanDEM-X lower elevations indicate a better penetration of the
radar signal. DEMs of differences (DoDs) allowed the identification of issues
inherent to the production methods of the analyzed DEMs, such as mast
oscillations in SRTM data and mismatch between adjacent scenes in ASTER GDEM
and ALOS AW3D30. A systematic difference in elevations between TanDEM-X 12m,
TanDEM-X 30m and SRTM was observed in the steep slopes of the coastal ranges,
related to the moving-window process used to resample the 12m data to a 30m
pixel size. Due its simplicity, it is strongly recommended to produce a DoD
with SRTM before using ASTER GDEM or ALOS AW3D30 in any analysis, to evaluate
if the area of interest is affected by these problems. The DoDs also
highlighted changes in land use in the time span between the acquisition of
SRTM (2000) and TanDEM-X (2013) data, whether by natural causes or by human
interference in the environment.Comment: 19 pages, 9 figures, supplementary material at GitHu
Using electronic resources to support dialogue in undergraduate small‐group teaching: The ASTER project
Learning through dialogue is an important element of UK higher education, supported by tutorial, seminar and workshop classes. Since 1998, the ASTER project has been exploring how Information and Communication Technologies support learning in small groups (http://cti‐psy.york.acuk/aster/). Electronic resources are developed and used in courses to support a wide range of learning needs, from delivery of content to interactive teaching tools and assessment. The manner in which they are integrated into a course dictates the extent to which they support and extend learning. The ASTER survey has identified the use of a range of new technologies to support learning through dialogue in a variety of contexts. Many of the uses are common across disciplines, though we have observed some differences in the range of tools used, and how they are implemented in and beyond the classroom. These differences are partly determined by the subject content of resources, and by the activities that ICT tools support. Another factor influencing this variation seems to be traditions of academic discourse. The findings suggest that educational technology needs to support both generic education practice, and the special needs of particular disciplines
Geo-structural map of the Laguna Blanca basin (Southern Central Andes, Catamarca, Argentina)
The Laguna Blanca basin is a rhomb-shaped basin located at the SE margin of the Puna plateau in the southern Central Andes (Catamarca, Argentina). An interactive analysis using remote sensing and field mapping enabled us to produce a geo-structural map at a 1:350,000 scale. Satellite images from multispectral sensors (ASTER and Landsat 7 ETM+) and medium resolution Digital Elevation Models (SRTM and ASTER GDEM) were used in order to recognize the structures and main lithologies, which were validated in the field and through laboratory tests (e.g. spectral analysis). The final result is a geo-structural map of the Laguna Blanca basin with a new geological unit subdivision, highlighting its tectonic origin, which appears to be related to a releasing stepover along N-S sinistral strike-slip master faults
Free global DSM assessment on large scale areas exploiting the potentialities of the innovative google earth engine platform
The high-performance cloud-computing platform Google Earth Engine has been developed for global-scale analysis based on the Earth observation data. In particular, in this work, the geometric accuracy of the two most used nearly-global free DSMs (SRTM and ASTER) has been evaluated on the territories of four American States (Colorado, Michigan, Nevada, Utah) and one Italian Region (Trentino Alto-Adige, Northern Italy) exploiting the potentiality of this platform. These are large areas characterized by different terrain morphology,
land covers and slopes. The assessment has been performed using two different reference DSMs: the USGS National Elevation Dataset (NED) and a LiDAR acquisition. The DSMs accuracy has been evaluated through computation of standard statistic parameters, both at global scale (considering the whole State/Region) and in function of the terrain morphology using several slope classes. The geometric accuracy in terms of Standard deviation and NMAD, for SRTM range from 2-3 meters in the first slope class to about 45 meters in the last one, whereas for ASTER, the values range from 5-6 to 30 meters.
In general, the performed analysis shows a better accuracy for the SRTM in the flat areas whereas the ASTER GDEM is more reliable in the steep areas, where the slopes increase. These preliminary results highlight the GEE potentialities to perform DSM assessment on a global scale
Reusable Software Components for Robots Using Fuzzy Abstractions
Mobile robots today, while varying greatly in design, often have a large number of similarities in terms of their tasks and goals. Navigation, obstacle avoidance, and vision are all examples. In turn, robots of similar design, but with varying configurations, should be able to share the bulk of their controlling software. Any changes required should be minimal and ideally only to specify new hardware configurations. However, it is difficult to achieve such flexibility, mainly due to the enormous variety of robot hardware available and the huge number of possible configurations. Monolithic controllers that can handle such variety are impossible to build. This paper will investigate these portability problems, as well as techniques to manage common abstractions for user-designed components. The challenge is in creating new methods for robot software to support a diverse variety of robots, while also being easily upgraded and extended. These methods can then provide new ways to support the operational and functional reuse of the same high-level components across a variety of robots
Molecular detection and characterization of phytoplasma associated with China aster (Callistephus chinensis) phyllody in India
China aster (Callistephus chinensis L.) is one of the most popular annual flowering plant grown through-out the world. Phyllody disease of China aster is a phytoplasma associated disease that induces severe economic losses. Phytoplasmal disease in China aster was assessed for phytoplasma by direct polymerase chain reaction primed by using phytoplasma universal primer pairs PI/P7. A 1.8 Kb DNA fragments encoding the portion of phyto-plasma 16SrDNA amplified by PCR was cloned and sequenced. Sequencing of the PCR product and BLAST analy-sis indicated that China aster phyllody phytoplasma strain shared maximum sequence identity (99%) with strains of Peanut Witches’ broom (16SrII) phytoplasma group. Phylogenetic relationship of 16SrDNA sequence of China aster phyllody phytoplasma strain in the present study confirmed association of Peanut Witches’ broom (16SrII) group of phytoplasmas with China aster phyllody disease in India
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